Technical Field
The instant disclosure relates to a headphone, and more particularly, to a dual-frequency coaxial headphone.
Related Art
As shown in FIG. 1, FIG. 1 is a side view of a headphone structure of prior arts. The headphone structure A of prior arts includes a signal line A1, a diaphragm A2, a permanent magnet A3, a voice coil A4, a magnetic component A5, and a yoke A6 all disposed in a headphone housing A10. The voice coil A4 is assembled to the diaphragm A2 and surrounds a periphery of the permanent magnet A3. A radial gap is kept between the voice coil A4 and the magnetic component A5. The permanent magnet A3 is sandwiched between the magnetic A5 and the yoke A6.
The signal line A1 is electrically connected to voice coil A4. When sound signals are inputted to the voice coil A4, the voice coil A4 generates magnetic fields according to the electromagnetic effect. The magnetic fields magnetically interact with the magnetic component A5 to have the diaphragm A2 vibrate such that the sound signals are converted to sound waves.
Generally, sound signals include high-frequency and low-frequency ranges for producing high-frequency and low-frequency sound waves by the vibration of the same diaphragm A2 of the prior headphone structure A. The high-frequency and low-frequency sound waves have different properties such as different wave lengths and amplitudes. Properly converting high-frequency and low-frequency signals to high-frequency and low-frequency sound waves having clear and distinct properties by merely the same diaphragm A2 is difficult. Therefore, sound converting process of the prior headphone structure A often causes intermodulation distortion between high frequencies and low frequencies. Prior arts also require frequency dividers for frequency division. Another issue of prior arts is that the material composed of the diaphragm A2 is uniform, which is not suit for converting different ranges of frequencies. A diaphragm properly produces high-frequency sound waves by faster vibrating and lower amplitudes. To a certain extent, the harder the material of the diaphragm, the better the high-frequency sound quality. In contrast, a diaphragm properly produces low-frequency sound waves by slower vibrating with longer wave lengths. To a certain extent, the softer the material of the diaphragm, the better the low-frequency sound quality. In other words, full range frequency sound waves produced by the single diaphragm A2 has mediocre quality. Features with respect to high-frequency and low-frequency sound waves are hard to be respectively emphasized. As a result, the produced sounds are not clear and distinct.